CN1911197B - Vacuum-formed film panels with a silky touch - Google Patents

Abstract

A vacuum formed film (26, 38, 50) that provides good rewet properties and provides a good silky feel or silky hand to the user, which may contain a plurality of apertures (28, 42, 52, 104). The holes may be elliptical, each having a major axis (14) and a minor axis (16). The pores may also be boat-shaped or oval-shaped, where the major axis of the pores is rounded at the end, and the major axes of the pores are aligned along the stroking direction (7) of the membrane. The holes define stroke direction shaped segments (34, 40, 58, 102) and transverse shaped segments (36, 46) in the region between the holes. The stroking direction forming section may be taller than the transverse forming section. Micro-ridges (106) may be formed on the shaped section. Each of the different membrane surfaces mentioned above contributes to a silky feel. Some or all of the above various looks can be combined to obtain a further improved silky feel.

Description

Vacuum-formed film panels with a silky touch

The patent application of the present invention is the international application number PCT/US 02/13160, the international application date is April 25, 2002, the application number entering the Chinese national stage is 02811340.3, and the name is "vacuum forming film surface with silky touch" A divisional application of the invention patent application for "chip".

Cross-references to earlier filings

This patent application claims priority over US Patent Application No. 09/876,440, filed June 1, 2001, entitled "VACUUM FORMED FILM TOPSHEETS HAVING A SILKY TACTILE IMPRESSION."

field of invention

The present invention relates to disposable absorbent articles. More particularly, the present invention relates to porous vacuum formed films which, when stroked by a user, possess certain properties which impart a silky touch or silky feel to the film.

Background of the invention

Advances in film forming technology have led to continued improvements in disposable absorbent articles such as disposable diapers, feminine hygiene products, and the like. "Film" is a general term for thermoplastic polymer sheets processed by various methods. The most common method of producing films is the extrusion process.

Cast extrusion and blown extrusion are commonly known processes in the film industry. In the inflation extrusion process, the circular die extrudes the expanded film bubble, and the film bubble is cooled by the cold air flow, and the cold air is blown on the circumference of the film bubble through the air ring. The bubble is then flattened in the nip and subsequently cut into flat sheets, which can then be reheated, embossed and otherwise manipulated. Blown film can be used to form master rolls of film that can be fed into a reheated vacuum formed film (VFF) process. See US Patent 4,151,240 to Lucas for this method. Furthermore, the use of cast web master rolls is also known.

In cast extrusion, a flat sheet is extruded from a slot die. The flat sheet is then cooled and set with different chill rolls. For example, US Patent 4,456,570 to Thomas proposes web extrusion using a direct melt vacuum formed film (VFF) process. In the vacuum formed film process, a pressure differential is applied through the forming screen. In the direct melt VFF process, molten sheet is extruded onto the forming zone of the forming wire. See Thomas, US Patent 4,456,570 for an example of a direct fusion VFF process. US Patent 4,151,240 to Lucas proposes reheating and partially melting the sheet while it is on the forming zone of the forming wire. The molten polymer preferably forms three-dimensional pores because the molten polymer is more easily drawn into the pores of the forming screen. Thomas USPN 4,456,570 and Lucas USPN 4,151,240 mainly use vacuum as the main source of differential pressure energy, which is used as working energy, which can transform a two-dimensional sheet into three-dimensional pores and open the pores in the membrane. During VFF formation, the polymer of the film usually undergoes a phase transition from a flattened molten state to a new three-dimensional crystalline state.

In some cases it is desirable to create a texture on the shaped section of the VFF. To form the texture on the forming section of the vacuum formed film, the forming section is provided on a textured forming wire. The texture on the forming screen is then added to the direct fused VFF film. Due to the vacuum pressure, textures are formed on the shaped section of the subsequently formed VFF. As mentioned above, vacuum pressure differentials can also induce 3-D pores, which form in the membrane.

The texture formed on the VFF may be formed in a pattern. Examples of embossed patterns include straight lines, pyramids, rhombuses, squares, and random rough surfaces. Also, more exotic patterns can be used, including exotic squiggly lines, spiral patterns, subtle petal shapes, and other decorative patterns.

Micropatterns can also be added to the master film using the reheated VFF process, either by cast embossing or blown embossing processes well known in the industry as described above. During reheating, external heat is applied to partially melt and form three-dimensional pores with holes. Part of the mother film rests on the forming section of the wire, which partially protects this part of the mother film from heat. Thus, only that portion of the film that is suspended over the openings of the meshes in the forming wire is not protected from heat at all. Therefore, the suspended part melts to form three-dimensional pores with holes.

When the film layer is applied to the forming wire, the mass of the film layer is typically about 25 to 80 times less than the mass of the metal mesh underlying the film layer. Because of the mass ratio of the film layer to the wire, the wire acts as a "heat sink" in the forming section region where the parent film is in intimate contact with the forming section of the forming wire. The heat passes through the film and is absorbed by the web so that no or negligible thermal deformation occurs in the area of the forming section. Therefore, any texturing pattern embossed on the master film remains in the finished VFF.

Films produced by the above method can be constructed of different materials with selected number of cells, embossing thickness, selected hole pattern, selected width of forming sections or spaces between holes, and can be formed in forming sections. Featured patterns on . The hole count is the number of holes arranged within a distance of 2.54 cm. Other variations may also be possible. Each configuration will exhibit different characteristics in terms of performance.

When measuring the percent open area of a VFF, any one of a number of computerized video devices available is typically used. The camera, after zooming in and comparing, can distinguish the hole and the forming section, and digitally process the data to calculate the percent opening area.

Unlike nonwovens (NW), which have a capillary effect on absorbing fluids, formed films are processed from polymer sheets that cannot transmit fluids unless formed films are made into three-dimensional porous sheets. Formed films can be tested for rewet. The lower the releaching value, the better. Generally, it is preferred that the product has a rewet value of less than 1 gram, "less than 1 gram". It has been found that products having a rewet value of 1 gram or greater are generally perceived by consumers as wet or damp in use.

Fluid acquisition speed is also important for functional patches. Products using top sheets may leak if the fluid acquisition rate is too low. Fluid acquisition speed is affected by several factors. The surface energy of the vacuum formed film is critical to the fluid acquisition rate. In addition, the fluid acquisition rate is directly related to the open area. In addition, "loft", or the necessary spatial distance between the fluid-containing absorbent core and the user's skin, must also have some measure to avoid a wetness factor of 1 gram or greater, which is determined by resoaking. Indicated by wet value. Simply stating that if there are larger openings, indicated by a high % open area, and smaller interspaces, indicated by a low height, the fluid is able to overcome a short space region through the center of the large pores, which results in counterflow, or Rewetting.

Table 1, below, was obtained from a selection of feminine napkin products from around the world that used a formed film coversheet. From the data in Table 1, a proportional relationship can be found. From these data, the apparent separation line of height to % open area (L/OA ratio) between the dry and wet coverage sheets would logically be around an L/OA ratio > 10.

The term "rewet" means that all of the fluid passes through the panel, and then "rewet" measures only the fluid that returns to the surface. However, with the variety of micro embossing, beading and punching involved with these materials, often forming "wells" that collect fluid at the surface, trapped fluid accounts for about 15% of the error in the data. Also, as with any reliable test method used, the method itself is subject to some error in the results, even within a particular material. This will serve to explain why the correlation is not exactly linear, when in theory, it should be.

The hole diameter is determined by the narrowest width of the holes, especially oval or elliptical holes, which can be determined as a function of the number of holes or the width of the shaped section. Depending on the number of holes and the width of the forming section, an approximate hole diameter or "support" span of the polymer sheet to be holed can be obtained.

Commonly known 60-hole forming screens generally have a hole diameter of not more than 200 μm. Since the proper amount of metal must remain between the holes in the forming screen (so that the forming screen will be strong enough to run in the VFF process), the hole size can be calculated as follows. As stated above, the cell count is the number of holes aligned within a distance of 2.54 cm (1 inch); thus, 2.54 cm/60 = 425 μm (1/60 = 0.0423 cm (.017 inch)) center to center. A range of metal forming segments of about 230 μm is required to obtain a strong mesh, leaving a nominal 200 μm pore size for a pattern of 60 holes per 2.54 cm (per inch).

In addition to rewet and fluid acquisition properties during use, it has been found that the hand or feel of the doughsheet is also important to the consumer. Silk has been known for centuries for giving it a unique and fine touch, no description other than "this feels silky". The term "silky" alone provides enough instructions for consumers around the world to appreciate what it means and to recognize whether a product feels silky to the touch, or just soft and cotton-like. Various fabrics such as felt, flannel, cotton diapers, polyester/cotton garment fabrics, wool, and silk were tested in repeated blind panel tests. The panel of experts easily discerned the Silky Touch (STI) of silk fabrics among other fabrics.

Over the years, the feminine hygiene napkin market has been divided into those favoring nonwoven coversheets and those favoring film coversheets. Market fragmentation occurs especially in Westernized countries. Consumers who prefer nonwoven types seem to like the cotton-like feel and comfort they feel.

However, users of the nonwoven type lose out on the dry cleaning of the VFF type. Nonwovens have capillary action due to the presence of many fibers in close proximity to the absorbent core. Wicking Facilitates the transport of fluids across the coversheet by capillary action of the nonwoven. Unfortunately, "wicking fluid" by capillary action can also work in reverse. Therefore, nonwovens are known not to provide good rewet values. Good rewet values indicate dry cleaning during use.

Consumers of preferred membrane types appear to like the improved cleanability and rewet resistance, especially those of VFF. Many VFF covering sheets have large pores that readily accept the semi-condensed material present in menses. The VFF also prevents the aforementioned rewetting of the upper surface of the membrane by the fluid. The prevention of rewetting comes from the excellent height of the VFF material. Thus, consumers who prefer prior art film types lose a bit of the cotton-like feel for cleanability derived from the presence of nonwoven fibers, which is particularly true of VFF. Films that provide both the perceived comfort of a nonwoven and improved cleanability and rewet resistance are desirable. Accordingly, considerable effort has been made to try to obtain the benefits of both types, and some have achieved market success; however, to date, no VFF has provided both cleanliness and silky feel.

Summary of the invention

The present invention relates to vacuum formed films that provide good rewet and provide a good silky feel or silky hand to the user. In one embodiment, the vacuum formed film has a plurality of apertures, the apertures being elliptical, each aperture having a major axis and a minor axis. In another embodiment, the aperture is boat-shaped with the ends of each end of the major axis rounded off. In another embodiment, the pores may be oval. The long axes of the pores are aligned along the stroking direction of the vacuum formed film. The holes define the area between the holes between the stroke direction shaped segments and the transverse shaped segments. In one embodiment, the stroking direction forming section is taller than said transverse forming section. In yet another embodiment, microridges are formed on the forming section to give the vacuum formed film a silky feel. The appearance of each of the above films contributes to the silky feel of the film. In further embodiments, some or all of the various surfaces described above may be used in combination to obtain a further improved silky feel. The vacuum formed film preferably has a height to open area ratio greater than about 9 and a rewet value of less than about 1 gram.

Brief description of the figure

Figure 1 is a perspective view of a feminine sanitary napkin incorporating the film of the present invention.

Figure 1A is a plan view of a section of forming wire having an oriented elliptical pattern.

Figure 1B is a cross-section of the formed film taken along line 1B-1b shown in Figure 1A.

Figure 1C is a cross-section of the formed film taken along line 1C-1c shown in Figure 1A.

Figure 2A is a plan view of another embodiment of a section of forming wire having an oriented elliptical pattern.

Figure 2B is a cross-section of the formed film taken along line 2B-2b shown in Figure 2A.

Figure 2C is a cross-section of the formed film taken along line 2C-2c shown in Figure 2A.

Figure 3 is a plan view of a section of film containing a pattern of oriented ellipses, wherein the film has a single plane on all formed sections.

Figure 4 is a plan view of a section of film containing a pattern of oriented ellipses where the film has the highest plane on the stroke direction forming section.

Figure 5A is a convex plan view of a section of membrane containing boat-shaped pores.

Figure 5B is a concave plan view of a section of membrane containing boat-shaped pores.

Figure 6A is a concave plan view of a formed film material containing micro-ridges on a formed section of the film.

Figure 6B is a convex plan view of a formed film material containing micro-ridges on a formed section of the film.

Figure 7 is a cross-section of the formed film material in Figures 6A and 6B taken along line 7-7 shown in Figure 6B.

Detailed Description of the Invention

In this invention, direct melting and reheating methods are considered equivalent for vacuum formed film (VFF). Because of melting, forming, and recrystallization within a three-dimensional morphology, each method can be used to form films in which the height direction of the pores is solid. Polymer sheets have a property, called "memory," whereby said polymer sheets tend to return to their original shape. Thus, if a polymer sheet is formed into a flat sheet and then pressed into a three-dimensional shape without melting and recrystallization, the polymer sheet will try to return to its original flat shape again under any subsequent application of stress. Firmness in the third dimension is important to achieve and maintain "height", which prevents rewetting.

49-70型用于测量高度。特性间的这种关系直接与再浸湿性能有关，并且这种关系是高度(以微米(μm)测量)除以百分开孔面积(例如17.3％)的简单计算。例如，正方形图案填充阵列(packingarray)上的每2.54cm(每英寸)60个圆孔，其百分开孔面积(OA％)可按照下列方法计算：When specifying VFF, two important variables are usually discussed, altitude and %AO. "Height" is defined as the top-to-bottom thickness of the vacuum-formed film, which is generally the necessary spatial distance between the fluid-containing absorbent core and the user's skin or the thickness of the vacuum-formed film. Height is generally measured in the same way as "embossed thickness" is measured in the polymer film industry. Embossing simply imparts a third dimension to the film, usually in a defined pattern and shape. A device commonly used for this measurement is called a "low load micrometer". The wide range of movement under low compression loads is used to ensure that the full depth of the pattern is measured and that the compression pattern does not give false readings. TMI manufactured here by TestingMachines, Inc. of Amityville, NY

Type 49-70 is used to measure height. This relationship between properties is directly related to rewet performance and is a simple calculation of height (measured in micrometers (μm)) divided by percent open area (eg 17.3%). For example, for a square pattern filling array (packingarray) with 60 circular holes per 2.54 cm (per inch), the percent open area (OA%) can be calculated as follows:

international unit:

OA%＝{((number of holes×number of holes [because of the square array] area of each hole, unit cm)÷(2.54cm) ² }×100

60 holes per 2.54 cm (per inch) have a diameter of 200 μm, 200 μm/10,000 μm/cm=0.02 cm diameter

· D/2 = radius, therefore, radius (R) = 0.02cm/2 = 0.01cm

· Area = πR ² = 3.14159×(0.01cm) ² = 0.00031cm ²

· Number of holes × number of holes = 60 × 60 = 3600

·{(3600×(0.00031cm ² ))÷(2.54cm) ² }×100＝ 17.3% opening area

US units:

OA%＝{((Number of holes×Number of holes [because of the square array]) the area of each hole, unit 2.54cm (inch))÷(2.54cm (inch)) ² }X100

The diameter of 60 holes per 2.54 cm (per inch) is 200 μm, 200 μm/(25,400 μm/2.54 cm (inch)) = 0.0199 cm (0.00787 inch) diameter

· D/2 = radius, therefore, radius (R) = 0.0199 cm (0.00787 inches)/2 = 0.01 cm (0.0039 inches)

· Area = πR ² = 3.14159 x (0.01 cm (0.0039 inches)) ² = 3.1 x 10 ^-4 cm ² (4.8 x 10 ^-5 inches ² )

· Number of holes × number of holes = 60 × 60 = 3600

·{(3600×(3.1×10 ^-4 ))÷(2.54cm(1 inch)) ² }×100＝ 17.3% opening area

For the present invention, it has been surprisingly found that it is also possible to obtain satisfactory Silky Touch (STI).

It has been found that STI can be improved by selecting a perforation count within a specific range of about 28 to 60, preferably 40. If fewer holes are present, it has been found that the user may perceive the individual presence of the holes, which may detract from the STI effect. The STI can be further modified with oval, boat or elliptical holes having a major to minor axis ratio of at least about 1.05:1.0 to about 6.5:1, more preferably in the range of about 1.5:1 to 4:1. STI can be further improved by aligning all major axes in substantially the same direction. For purposes of this application, the stroke direction (SD) is defined as the direction along the length of the final product, such as a feminine hygiene napkin or the like. Figure 1 shows sample 5. Arrow 7 shows the direction of stroking. The stroking direction is generally the direction in which a consumer strokes the material when evaluating a film. Preferably, the direction of stroking is aligned with the direction in which the user is most likely to be rubbed back and forth during use, ie generally front to back. By performing the steps described above, discernible panel test results for STI were obtained compared to other VFF panels and synthetic silk-like nonwovens previously known in the art.

Also, those skilled in the art generally consider "machine direction" (MD) to be the direction of processing in the production of formed films, and with few exceptions, in the conversion of formed films into topsheets on absorbent assemblies. MD is the direction in which the sheet of material is continuously moved along the machine, and as it relates to the forming wire, MD is the circumference of the wire and "transverse direction" (TD) is the length of the wire from one end to the other. As commonly understood, the forming wire rotates about a fixed seal. Thus, the circumferential direction is the direction in which the feed film is continuously moved in the "machine direction" along the machine. Variations from this standard will be appreciated by those skilled in the art when they are not commonly used or used, and therefore, the above should not be considered as limitations of the present invention.

On most conversion lines where VFF is used as a topsheet, the diaper or pantiliner or bandage or any absorbent component being processed will have the MD of the topsheet along the length or largest dimension of the product. Especially for feminine sanitary napkins, the difference in length and width is important. When the sanitary napkin was handed to the women in many of the tests, they generally stroked the top sheet along the length of the product as shown in Figure 1 . Thus, it will often be the case that stroke direction is synonymous with portrait orientation, although this need not be within the scope of applicant's invention. For the consumer, when the consumer wants to know how the product feels in use, the first touch is obtained by stroking the face sheet in the manner described above.

The length also conforms to the anatomy of common disposables. Since the disposable is usually placed in the groin between the legs, there is little possibility of lateral or TD motion. If the product moves during the natural movement of the user, the movement will almost always appear on the MD causing a "stroking" effect of the face sheet on the skin. From all of these relevant factors, as noted above, it can be seen that the terms "MD" and "SD" are often used synonymously. STI effect is obtained with stroking motion. Therefore, refer to the "stroking direction" (SD).

For purposes of this application, the term "oval" shall relate to a circle having a major and minor axis which is substantially curved along a line along the major axis. The term "elliptical" will be distinguished, the line along the major axis being substantially straight. Hereafter, the ratio of the major axis to the minor axis is referred to as SD:TD, where SD is the arrangement in the direction of stroking of the major axis and TD is the transverse direction of the minor axis. Although not necessary to obtain the STI effect, it has been found that the STI effect is enhanced if the centers of the major axes are co-aligned with each other.

Additionally, although not necessary to achieve the STI effect, the STI effect can be further enhanced if the shaped segments on SD are on a slightly higher plane than the shaped segments on TD. Moreover, STI can be produced by this means alone. When compared to a single plane material of the same configuration, a higher grade of STI will be obtained if the SD forming section is at a slightly higher plane. A difference of only 15 μm has been found to show little difference, although a difference of 35 μm is preferred. If the difference between the SD and TD forming sections of the film is greater than 145 [mu]m, then there are problems with the strength of the forming screen, especially in the case of finer cell counts. It can also cause winding problems, such as roll clumping due to nesting. Since the SD forming section is raised, the hole geometry is less required. Many polygonal shapes will also work, such as squares, hexagons, pentagons, and others.

The plane height difference between the SD forming plane and the TD forming plane can be achieved by processing the forming net with cutting tools, grinding, etching, cutting with energy beams, or adding wires to change the outer contour of the forming net to form a double-plane forming section. Additionally, other means can be used to vary the height of the SD shaped section.

It is also not necessary, but preferred, to add various textures to the shaped sections to enhance the effect of the STI. It is more preferred to add micro-ridges (MR) of specific height and spacing. Films with micro-ridges received a very high STI panel test rating when micro-ridges were used on films with 28 or more perforations per 2.54 cm (per inch), especially films with 40 hexagonal patterns hour. To form the pattern of micro-ridges, the pattern is typically etched into the forming section regions of the web. Micro-ridges will readily form on the shaped section of film, as long as direct channels for gas discharge remain in the spaces between the micro-ridges. Air venting requirements apply to all patterns in which a formed section of film is to be textured. If the molten film covers the film pores, forming a seal around the periphery of the film pores, thereby closing the gas discharge channels, will prevent the film from being sucked into the micro-patterned depressions. Therefore, it is possible to prevent the film from sticking to the shape of the micro-pattern depressions.

All or some of these features and enhancements, such as co-alignment of the center of the major axis, raised SD forming sections, and micro-ridges in general, can be combined to produce a VFF material that will be used in most of the expert panels convened to test the product The STI effect is displayed in the members. Other important aspects are maintaining an adequate VFF pore size and product quality for transporting fluid through the topsheet into the absorbent core (especially viscous menstrual fluid), as well as maintaining a desirable VFF "height to percent open area ratio" such that Good rewet values were obtained.

In addition, it has been shown that a preferred cell number range can help achieve a desired STI. As stated above, the number of holes is the number of holes arranged in a length of 2.54 cm. The higher the hole count, the greater the number of holes that are packed together. The lower the cell count, the fewer the number of cells in a given unit of length and/or square area. The apertures or three-dimensional apertures may be patterned in any of a variety of arrangements which are advantageous for the desired purpose. Once the arrangement is chosen, it is then possible to count the number of holes per 2.54 cm of length to determine the "hole count".

Referring now to FIG. 1A, there is shown a section of forming wire 10 showing an oriented array of oval patterns. In a preferred pattern, oval holes or holes 12 have a major axis 14 and a minor axis 16 . The major axis 14 is aligned in the machine direction (MD) indicated by arrow 18 . Transverse direction (TD) is indicated by arrow 20 . In a preferred embodiment, the ratio of the lengths of major axis 14 to minor axis 16, "SD:TD", is about 3:1. Preferably, all major axes 14 are aligned with each other, all along the longitudinal direction 18 . Furthermore, all minor axes 16 are correspondingly aligned along TD20. The area between the holes 12 is the SD shaped section 22 and the TD shaped section 24 .

Referring now to FIG. 1B, there is shown a cross-section of forming wire 10 taken along line 2-2 of FIG. 1A. FIG. 1B is an embodiment of the forming wire 10 in which the SD forming sections 22 are located at a higher level than the TD forming sections 24 . The SD forming section can be seen more clearly in Figure 1C, which is a cross-section of the forming wire 10 along line 1C-1c in Figure 1A.

Referring now to Figure 2A, there is shown a section of forming wire 10' which exhibits an oriented array of oval patterns. In a preferred pattern, oval holes or apertures 12' have a major axis 14' and a minor axis 16'. The major axis 14' is aligned in the machine direction (MD) indicated by arrow 18. The transverse direction (TD) is indicated by arrow 20 . In a preferred embodiment, the length ratio of the major axis 14' to the minor axis 16', i.e. "SD:TD", is about 3:1. Preferably, all major axes 14' are aligned with each other, all along the longitudinal direction 18. Furthermore, all minor axes 16' are correspondingly aligned along TD20. The area between the holes 12 is the SD shaped section 22 and the TD shaped section 24 .

Referring now to Figure 2B, there is shown a cross-section of the forming wire 10' taken along line 2B-2b. Figure 2B depicts an embodiment wherein the upper surfaces of the SD shaped section 22' and the TD shaped section 24' are in the same plane. The SD forming section can be seen more clearly in Figure 2C, which is a cross-section of the forming wire 10' along line 2C-2c in Figure 2B.

Referring now to FIG. 3, a single-plane VFF 26 is shown. The VFF 26 is made from a forming screen having an elliptical pattern in which the major axes 28 of the holes 30 are aligned in the MD. The pattern shown in Figure 26 is a pattern of 40 holes per 2.54 cm (per inch) when counting holes in TD. The length of the hole 30 of the vacuum formed film 26 is about 750 μm in SD or the direction of the major axis 28 and about 250 μm in the direction of the TD or the direction of the minor axis 32, and the thickness of the hole is from the top to the bottom of the three-dimensional hole 30 , that is, the height, is about 345 μm. VFF26 has an open cell area of 14.5%. Therefore, the ratio of height to percent open area of VFF26 is about 24. VFF26 had a rewet value of 0.08 grams. The difference between the upper surfaces of SD shaped segments 34 and TD shaped segments 36 in biplanar material 26 is about 20 μm.

Referring now to FIG. 4 , a multi-planar VFF 38 is shown in which the highest plane is the upper surface of the SD shaped section 40 . The VFF 38 is made from a forming screen having an elliptical pattern in which the major axes 42 of the holes 43 are aligned in the MD. The pattern shown in Figure 6 is a pattern of 40 holes per 2.54 cm (per inch). The pores 43 of the vacuum formed film 38 have a length in the direction of the SD or major axis 42 of about 750 μm and a length in the direction of the TD or minor axis 44 of about 250 μm. The thickness of the hole 43, which is the height from the top to the bottom of the three-dimensional hole 43, is about 345 μm. The percent open area of VFF38 is 14.5%. Therefore, the ratio of height to percent open area of VFF38 is about 24. VFF38 had a rewet value of .08 grams. The difference between the upper surfaces of SD shaped segments 40 and TD shaped segments 46 in biplanar material 38 is about 20 μm.

Referring now to FIGS. 5A and 5B , another embodiment of a VFF, which will be referred to as a "boat shaped hole" (BSC) 50 VFF, is shown. The "hole boat" embodiment 50 preferably has 40 holes per 2.54 cm (per inch). "Boat hole" refers to an oval hole 52 with a rounded tip. Bore 52 has a major axis 54 and a minor axis 56 . Preferably, the ratio of the lengths of the major axis 54 to the minor axis 56 of the bore is about 1.75:1. It has been found that rounding the ends of each oval hole, as shown in Figures 5A and 5B, or oval holes, as shown in Figures 3 and 4, further enhances the STI effect, especially in uniplanar materials. The BSC embodiment 50 of FIGS. 5A and 5B contains pores 50 that are approximately 425 μm in length along the major axis 54 and approximately 240 μm in length along the minor axis 56 . The BSC membrane 50 had a height of 315 μm and an open area of 22%, which gave a ratio of height to % open area of 14 and a rewet value of 0.15 grams. Of course, the above scales are illustrative and other scales may be used.

An additional feature of the BSC embodiment 50 is that the major axes 54 of the boat-shaped or three-dimensional pores 52 are aligned along the SD, but not co-aligned with each other, ie, the pores 52 exist in a "staggered" arrangement. Thus, SD shaped section 58 is not straight, like SD shaped sections 34 (FIG. 3) and 40 (FIG. 4) of VFF films 26 and 38, respectively. Films with biplanar forming sections, such as the embodiment shown in Figures 1A and 1B, are not preferred for the staggered BSC embodiment, as it has been found that when all SD forming sections, such as 34 and 40, are co-aligned with each other , which is best suited to obtain biplane forming segments. Although these variations are less preferred, it has been found that the panelists are still able to get significant STI from the 40 cells per 2.54 cm (per inch) BSC (when counting cells in TD) embodiment 50. Applying a random matte texture to the shaped section can further strengthen the material and slightly improve the material's Panel STI grade.

While it is known that adding any of the possible VFF textures described above to a shaped section will contribute to the improvement and elimination of the haptics characteristic of plastic-type materials, it has surprisingly been found that "micro-ridges" (MR) alone are Capable of producing a palpable STI. Referring to Figures 6A, 6B and 7, a top view of VFF 100 (facing the user, Figure 6A), a photomicrograph of a bottom view of VF 100 (facing away from the user, Figure 6B), and an enlarged view of a cross-section of VFF 100 (Figure 7) MR of the present invention. VFF100 has 40 hexagon patterns. To form the texture on the forming sections 102 of the VFF 100, the forming sections of the forming wire used to process the VFF 100 are ground to be substantially flat to accept the pattern of micro-ridges in the forming section regions of the etching forming screen. As a result, the shaped section 102 formed between the holes 104 has micro-ridges 106 . The machine direction (MD) or stroke direction (SD) is indicated by arrow 108 .

When the micro-ridges 106 are inclined, ie aligned at an inclination angle 110 from SD 108 . They preferably have their own differences, with different heights and spacing, so as to have the best STI effect. The angle of inclination 110 may be 5° to 80° to achieve some effect, but the preferred range for the angle of inclination 110 is 30° to 60°, with 45° being ideally used. The height of MR 106 may be in the range of 5 μm to 75 μm, but a preferred range is 5 μm to 35 μm. Ideally, the height of MR106 is 20 μm. The spacing between micro-ridges 106 may be in the range of 25 μm to 250 μm, but is more preferably in the range of 50 μm to 150 μm, most preferably using 95 μm spacing. The micro-ridges 106 must also remain "individualized". If the micro-ridges 106 become interconnected, the micro-ridges 106 will not be able to produce the desired STI, but instead the micro-ridges 106 will exhibit a flat and plastic-like feel.

Test Data

Various formed films were tested for Silky Touch (STI) by 10 panelists. The results are shown in Table 2 below. Panel Method According to AATCC (1997) Evaluation Method 5, Fabric Hand: A Guide for Subjective Evaluation of Fabrics, American Textile Chemist and Dyer's Technical Handbook Vol. 72 (pp. 352-354), Research Triangle Park, NC; and ASTM (1968 ) Handbook of Sensory Measurement Methods, ASTM Special Technical Bulletin 434, 1968, pp.3-5.

The evaluation method used normal pads of standard thickness and materials providing standard compressibility. The values for thickness and compressibility are not particularly critical as long as the values are consistent. The pads were cut into rectangles measuring 7.62 cm long and 3.81 cm wide. Wrap completely with film and seal with tape as if wrapping a present, leaving a continuous smooth area of material on one side, the continuous smooth side containing the test side. Panelists wash their hands to keep the sample free from soiling that could cause anomalous differences between the first panelist and the tenth panelist when the sample is passed from one panelist to another hour.

Samples are numbered by inspectors, such as numbers or letters, but no paste is provided to prevent prior bias from panelists. Panelists were asked to rate the samples on a scale of 1 to 10, with 1 being the most silky and 10 being the least silky.

包含在内也是基于此目的。In the test data in Table 2 below, except for one product, the rest are all embodiments of porous membranes, except for "Unicharm's TS Threads on NW". The Unicharm product is not a formed film product, but it is included in Table 2 because it is known in Asia as a feminine napkin face sheet to cause a good STI. It is constructed by an unnamed method in which rayon filaments are glued to the upper plane (skin contacting side) of the nonwoven sheet. Perforations are perforated through the material to significantly increase fluid acquisition rates. It is considered to have a fluid acquisition rate above 3.0 grams. Unicharm products are included here to help get a more robust reading on the apparent separation line tested by an expert panel between STI and non-STI materials. Add Comfort Silk

It is also included for this purpose.

是机械成形的多孔膜，但不是VFF。市场上它也被认为是“如丝般的”。而且，Comfort Silk的列入有助于区别STI和非-STI。Comfort Silk

It is a mechanically formed porous membrane, but not a VFF. It is also considered "silky" in the market. Moreover, Comfort Silk The inclusion of helps distinguish STI from non-STI.

Reviewing the data, it is generally accepted that an average rating of ≤5.0 for the ten panelists for the film indicates that the STI is discernible. The number of No. 1 ratings given by the panelists can also be used as an indication of the STI that has been generated.

Table 2

experimenter MD Ellipse 40Hex flat w/ micro ridges 40BSC Unicharm's TS Filament on NW silky touch Always average 1 6 3 2 5 1 8 10 2 4 1 3 7 2 10 6 3 1 2 4 5 3 9 10 4 2 1 6 3 5 8 10 5 3 1 6 4 5 10 8 6 5 1 3 6 2 9 7 7 1 4 7 6 3 5 10 8 2 1 6 4 5 8 10 9 6 1 5 4 2 10 8 10 5 3 1 6 2 9 10 average 3.5 1.8 4.3 5 3 8.6 8.9

Samples for the filament test are rated from 1 to 10.

1 = "most silky": 10 = "not silky"

Another important test for comparing different films is the "Rewet Test". To test rewettability a test fluid is used which contains two parts of Pepto-Bismol and one part distilled water. A sample assembly is formed by placing a 12.7 cm wide by 12.7 cm long piece of vacuum formed film or nonwoven face sheet on 3 stacks of absorbent media with the wearer side up and the garment side down. 2 ml of test fluid was pipetted onto the center surface of the dough sheet. In seconds, use a stopwatch to record the time it takes for all the fluid to pass through the patch. This part of the test briefly describes the fluid acquisition rate. After the initial wetting, an additional 15 ml of test fluid is applied to the center surface of the dough piece. A 3.63 kg (8 lb) rewet load, 10.16 cm long by 10.16 cm wide base, was placed on top of the dough sheet for 3 minutes to allow the fluid to fully spread into the center pad. Then, with an additional 3.63 kg (8 lbs) rewet load, two pre-weighed absorbent papers were pressed against the dough sheet for two minutes. The amount by which the weight of the absorbent paper increases is measured in grams as rewet, which reflects the amount of fluid that can flow back and overcome the spatial separation of the topsheet material. It has been found that using this fluid to measure and obtain speed and rewet data correlates well with comparative data obtained by testing the same VFF material by this method or an undisclosed method used to produce feminine sanitary napkins Products used by large companies.

Table 3 below, comparing existing products, demonstrates that embodiments of the present invention provide superior STI while also maintaining the L/OA ratio shown as a function of rewet:

table 3

product Height μm Open area% Ratio of L/OA rewetting grams STI(Y/N) Always 550 32.0 17.0 0.05 N Equate 455 28.5 16.0 0.15 N ComfortSilk 115 28.5 4.0 1.25 Y SD Ellipse 38 345 14.5 23.8 0.08 Y 40 holes BSC 50 315 22.0 14.3 0.15 Y

It is therefore considered that the operation and construction of the present invention will be apparent from the foregoing description. While the apparatus and constructions shown or described have been said to be preferred, it will be apparent that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims (3)

1. A vacuum formed film comprising: a plurality of holes, each hole having a major axis and a minor axis, the major axes being aligned in a common direction; The hole has an oval, boat or ellipse shape, and the ratio of the major axis to the minor axis is 1.05:1-6.5:1. 2. The vacuum formed film of claim 1, wherein the vacuum formed film has a cell count of 28-60 per inch. 3. The vacuum formed film of claim 1, further comprising a formed section between said apertures, said formed section comprising micro-ridges.

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